Repair or Replace: Evaluating the Best Option for Your Furnace

Furnaces are reliable pieces of machinery, and we often forget about them as they work steadily along in the background. But when your furnace is making weird noises, taking too long to come on, or seems to not be doing anything at all, you may be wondering whether it is time to replace or repair your furnace. 

You should replace your furnace when repairs exceed half of the cost of buying a new one. This is especially true if your system is older than 15 years. However, furnace replacement can be costly, so the best thing to do is consult with a professional to understand if repairs are a possible alternative. 

The decision of whether to replace your furnace or repair it is not an easy one to make. Whenever there is an issue with an older furnace, there will always be many factors that you must weigh against each other. In order to help you make the best decision, here is some information you should consider.

Reasons To Replace Your Furnace

Replacing your furnace is a costly endeavor, and most of the time, it is probably more cost-effective to repair it. If you are not sure of what you should do, you should consult with a professional and see what the best option for your home is.  

Certain circumstances make it necessary to consider replacing your furnace (such as wanting to switch to an oil or gas furnace). Among other things, if you find yourself facing a furnace that is inflating the cost of energy, or you are facing expensive repairs, making replacement a serious option. Here are some factors that may lead you to replace your furnace system.

1. Your Furnace Is Emitting Carbon Monoxide

If your furnace is emitting carbon monoxide, it poses a safety hazard to your home. Evacuate your home immediately and call the fire department so that they can take care of the issue.

Carbon monoxide is a clear, odorless gas. While carbon monoxide is naturally present in the air you breathe, there are only trace amounts in the air. When carbon monoxide starts to build up, it is toxic to humans.

Carbon Monoxide emitting from furnace

Signs of excessive carbon monoxide in your home include headaches, dizziness, trouble breathing, and nausea. Extended exposure to carbon monoxide can also lead to death. So if your furnace is emitting carbon monoxide, it is time to replace your system.

2. Your Furnace Is Old

Regardless of which type of furnace you use, most sources agree that the average lifespan of a system is 15 years old. If your furnace begins to experience issues and it is past this age, it is likely a good time to replace your furnace rather than repair it.

Old Furnace
Old Furnace

That being said, age should not be the sole determining factor in your decision.  Some furnaces can last longer than this, especially if they are well maintained. If your furnace has had minimal issues over its life or if the cost of repair is minimal, then consider repairing your furnace rather than replacing it.

3. Your Furnace Makes Loud Noises

If your furnace is making loud noises, there is likely a serious issue. Popping, screeching, squealing or other noises could mean your furnace is overheating.  An overheating system will cause its internal components to expand and scrape against each other, causing internal damage.

However, your furnace can also make noises for other reasons, such as dirt entering the system or a faulty sensor causing a delayed ignition. If these problems are taken care of quickly, then the cost of repair can be kept at a minimum. If you hear your furnace making noises, turn it off and try to locate the source of the problem before you consider a replacement.

4. The Cost Of Repair Is Over Half The Cost Of A Replacement

If the cost of repair is more than half the cost of replacing your system, then don’t even bother with the repair, especially if you have an older furnace. This is probably the best test of whether or not to replace your furnace.  

As a furnace ages, more of its parts will begin to fail through wear and tear. If you have an especially costly repair, replacement might save you the cost of replacing those systems.  

In addition, your new furnace is more likely to be energy efficient. Over the life of your system, the cost savings in energy will pay for the new installation. 

5. Your Heating Bills Have Gone Up Drastically

If you have a well-maintained system but your heating bills are skyrocketing, this is a sign that your system should be replaced. As your older system ages, it becomes less efficient. It needs more energy to heat your home, which in turn will raise your energy bills.

High Electricity Bills
High Electricity Bills

Regular maintenance will keep your system running efficiently and keep your energy costs down. But if your bill is going up by several hundred dollars in the span of a month or two, then replacement is cheaper than running your old furnace. Replacing your system will likely reduce your energy bills to levels that will pay for your new system in time.  

6. You Are Experiencing Humidity Issues

If you are experiencing humidity issues while your furnace is running (either too little or too much) then your furnace is not functioning as it should. Your furnace dries the air as it works as a byproduct of its normal function.  If your home is too dry or too humid, it can cause issues for you and your home.

Too little moisture in the air can cause headaches and bloody noses, as well as make parts of your home shrink and crack. Too much moisture in the air can encourage mold growth. 

If the problem is mild enough, you can remedy the problem with a humidifier or dehumidifier, but if the problem is severe, you may need to consider a new furnace.

Reasons To Repair Your Furnace

When you have an aging system that is costing you money or threatening expensive repairs, replacement makes a lot of sense. However, repairs should always be given some thought, as they may be the cheaper option for you after all. 

When issues with your furnace are caught early on, you help yourself because the cost of repairs will not be as high. In addition, a problem that looks to be expensive may be something minor, such as a broken thermostat or dust in the system. If you are thinking about replacing your furnace, here are some things to consider that may lead you to repair it instead.

1. You’re Planning On Selling Your Home Soon

If you are planning on selling your home in the next few years, that expensive repair may be worth the cost after all, especially when you will not be around long enough to recoup the costs on your energy bill.  However, also consider that replacing your furnace may increase the selling value of your home.

2. Your Thermostat Is Broken

If your furnace appears to be costing you hundreds in energy bills, the culprit may not be the furnace after all. A broken thermostat is not able to regulate the temperature of your home. It is a common issue and is not only easier to repair, but it is also cheaper to fix at a cost of about $100.

Broken Thermostat

3. Excess Noise Due To Ductwork Issues

As it turns out, an overheating furnace is actually one of the less likely reasons your furnace is making noise. If you are hearing banging, screeching, or whistling coming through your vents, it is possible that the noise is due to damage in your ducts rather than in your furnace.

How Long Does A Furnace Last?

Many figures are thrown around as to the lifespan of a furnace, but 15 years is the agreed-upon average. Furnaces can last longer than this, however – upper ranges include 20 years, 30 years, and in extremely rare cases, 40 years. 

A number of factors can help extend the life of your system. Proper instillation, humidity, and ventilation can contribute to this, and certain makes and models have reputations for having long lives.  

However, the number one thing that can ensure your furnace lasts a long time is making sure that it is properly maintained.  Regular quality tune ups will help your system run efficiently and decrease wear and tear.

How Much Does It Cost To Repair My Furnace By Part?

The cost of repairing a furnace will usually be at least a few hundred dollars, though some repairs are more expensive than others. Thermostats, for example, are relatively cheap to repair, while a broken heater exchange may leave you considering replacing the furnace system entirely.

The good news about repairs is that most of the parts of your furnace are expected to last just as long as your furnace does, which means that your furnace has a relatively low failure rate. This failure rate drops even further with a properly maintained system. Here are some of the more common repairs that are needed by a furnace and their costs.

1. Thermostat

The cost of thermostat repairs depends on the type of thermostat you have. A basic thermostat may cost as little as $50 or less, though ‘smart’ thermostats can get pricy.  Here is a price chart of what a new model might cost (not an exhaustive list):

Thermostat ModelsPrice
KING Hoot WiFi Line Voltage DP Thermostat$540
Google Nest Learning Smart Thermostat w/ Wifi$250
ecobee Smart Thermostat w/ Wifi$190
Emerson 5-2 Day Programmable Thermostat$25

2. Blower Motor

The blower motor is the part of your furnace that pushes air throughout your home. There are two types of motors you can get – a permanent-split compressor blower motor which runs about $700, or variable-speed blower motors which costs around $1800.  Variable-speed motors have a longer life expectancy and offer you more control over your furnace.

Blower Motor
Blower Motor

3. Draft Inducer Motor

While the blower motor moves air throughout your house, the draft inducer motor moves the air in your furnace. They are the motors responsible for running the fans that send waste gases such as carbon monoxide out of the flue pipes.  Draft inducer motors have lifespans between 12-15 years and cost around $800.

Draft Inducer Motor

4. Flame Sensor

The flame sensor is the metallic rod that detects the flame inside the unit – if there is no flame, it turns the gas off. The flame sensor varies widely in price, depending on the make and model of your furnace – it can be as little as $75 and as much as $250.

Flame Sensor

5. Gas Valve

The gas valves are what pass the fuel to the burners. The cost of these gas valves depends on the make and model of your furnace but typically runs between $600 and $1000. While pricy, you can expect your gas valves to last you the life of your furnace, so you will probably not have to replace these.

Gas Valve

6. Control or Circuit Board

Depending on the complexity of your system, a replacement circuit board can cost you between $550 and $1,100. These circuits are the brains of your furnace. The most common cause of failure for circuit boards is moisture in the air, so keeping your circuit board in a relatively dry area can help to increase its life.

Circuit Board

7. Flue Pipe

Flue pipes costs can vary based on length, material, and ease of installation, but will average $600 for a new installation. The flue pipe is the part of your furnace hazardous and waste gases are pushed out through. Properly maintained pipes can last you the lifetime of your furnace or longer.

Flue Pipe

8. Transformer

Another low component of your furnace with a low failure rate is the transformer. Transformers will cost an average of $400. Transformers are what supply your furnace with electricity, and as long as your system is free of electrical stress, your transformers will last you the life of your furnace.


9. Oil Combustion Chambers

There are two parts to the oil combustion chambers – the part that holds the oil, and the combustion chamber itself. Together, these chambers are what produce heat for the furnace.

Oil Combustion Chambers

The combustion chamber is the more expensive part, costing between $200 to $600. The oil chamber costs between $100 to $200.

10. Heat Exchanger

Possibly the most expensive part of your furnace is the heat exchanger, which can cost up to $3,500 new. Repairing the heat exchanger is possible, but is not necessarily an efficient solution. This is the one component in your furnace that may cause you to think about replacing your furnace rather than repairing it.

Heat Exchanger

11. Coils

The evaporator coils aren’t actually part of the furnace (they actually belong to the air condition system), but the coils will make use of the furnace’s blower. They absorb heat for the blower, which delivers the heat to the air ducts. Replacing the coils varies in cost between $600 to $2000. 


How Much Does It Cost To Replace My Furnace?

The cost of replacing the furnace depends on the type of furnace that you are considering. Regardless of the type of furnace you get, you can expect to spend at least $3,500 on a new system, plus the cost of installation.  Installation services can run anywhere from $900 to $3,000 for labor costs, which you will probably want to ensure that it is installed correctly.

Furnace TypeAverage cost to replace
Gas$2,000 – $5,200
Electric$1,900 – $5,600
Oil$2,500 – $6,000
Propane$2,200 – $5,700
Coal$4,500 – $10,000
Mobile Home Furnace$950 – $4,500

Should I Repair Or Replace My Furnace?

Whether you should repair or replace your furnace depends on your individual situation, though repair is usually the best option. If the actual cost of repair is 50% or more than the cost of replacing your furnace, you should consider replacing your furnace, especially if your furnace is more than 15 years old.

The repair of your furnace is usually the cheaper option, and most of the parts have a longevity that is on par with your furnace. But if your furnace is starting to cost you hundreds in energy bills, you should consider a replacement. If your furnace is emitting carbon monoxide, then replacement is a necessity.


When you are considering whether to replace or repair your furnace, there are a lot of factors at play that you must consider. More often than not, a repair makes more sense than completely replacing your system. But if you are not sure, the best thing to do is consult with a professional and let them advise you on the best option for your home.